After 37 years and 136 tanks delivered, Lockheed Martin (NYSE: LMT) production of the Space Shuttle External Tank (ET) has come to an end at the NASA Michoud Assembly Facility in New Orleans.

The final tank arrived at Kennedy Space Center on September 27, ending a production program that began with contract award on September 5, 1973. Two shuttle launches remain in the program -- on November 1 this year and February 26 next year.

"The Space Shuttle has provided a pathway for America's leadership in space exploration," said Manny Zulueta, Lockheed Martin vice president & site executive at Michoud. "Working alongside NASA on the External Tank has been a gratifying and historic experience for our employees."

Some of the more significant ET milestones include:

June 29, 1979 -- rollout of the first ET, commonly referred to as the Heavyweight version – weighing 76,000 pounds

September 10, 1982 – rollout of ET-8, the first Lightweight Tank – weighing 66,000 pounds. The 10,000-pound weight savings from the Heavyweight version equated to increasing the shuttle payload capacity by an additional five tons per mission.

June 2, 1998 – launch of ET-96 and the first Super Lightweight Tank – weighing 58,500 pounds. The 7,500-pound weight savings from the Lightweight version was critical in enabling the Space Shuttle to carry components to build the International Space Station.

August 29, 2005 – Hurricane Katrina strikes the Michoud facility, causing more than $100 million in damage. A NASA-Lockheed Martin ride-out crew keeps the pumps operating and saves the facility from flooding. Their efforts preserve tens of millions of dollars of one-of-a-kind tooling, thus protecting the human space flight program. Michoud reopens to limited production less than five weeks later on October 1.

With the end of ET production, workforce reductions have been taking place as discrete elements of work have concluded. On January 1, 2010, Lockheed Martin employed 1,438 employees at the Michoud Assembly Facility. The current workforce stands at approximately 600. The majority of that number includes employees working on the Orion Crew Exploration Vehicle program and those who have Launch and Landing responsibility for the final Space Shuttle launches.

At 154 feet tall, the External Tank stands 15 stories, measures nearly 28 feet in diameter, and weighs close to 1.7 million pounds when filled with propellant. During launch, the ET delivers 535,000 gallons of liquid hydrogen and liquid oxygen propellants to the shuttle's three main engines, thereby powering the Orbiter into space. The tank then separates from the Orbiter and burns up upon reentry into the atmosphere.

Headquartered in Bethesda, Md., Lockheed Martin is a global security company that employs about 136,000 people worldwide and is principally engaged in the research, design, development, manufacture, integration and sustainment of advanced technology systems, products and services. The Corporation's 2009 sales from continuing operations were $44.5 billion.

: Lockheed Martin rolls out the first Super Lightweight Tank (ET-96) version of the External Tank on January 16, 1998 in New Orleans.